As you plunge into the cool, clear water of the ocean, you may feel as if you are alone, floating peacefully within this vast blue world. However, the ocean, along with Earth’s many other aquatic ecosystems, is actually teeming with microscopic life. Phytoplankton, also known as micro-algae, can be found living near the surface of a body of water, such as an ocean, sea, or lake. Despite their small size, these microbes perform a variety of functions that are essential to all life and many natural processes on Earth.

One of the many functions that are performed by phytoplankton is the production of oxygen. Similar to terrestrial plants, phytoplankton rely on the sunlight absorbed by their chlorophyll, carbon dioxide from the atmosphere, and water to perform photosynthesis, which they use to create their own food to sustain themselves. Oxygen is then generated as a byproduct of this process. As phytoplankton are responsible for nearly 80% of the oxygen production on Earth, they are a vital source of oxygen for many organisms. These microbes also play a vital role in the regulation of the carbon cycle. Without their constant consumption of carbon dioxide, there would be a drastic increase in the concentration of carbon in the atmosphere. The increase in carbon levels would accelerate climate change and worsen global warming.

Another function performed by phytoplankton is their major role as the base of many aquatic food webs. These microbes are primary producers that serve as the main source of food for primary consumers such as zooplankton and copepods. Further up the food web are the secondary consumers who feed on primary consumers, tertiary consumers who feed on secondary consumers, and lastly quaternary consumers who feed on tertiary consumers. Since phytoplankton form the foundation of many aquatic food webs, an imbalance in phytoplankton levels can lead to major disruptions in aquatic ecosystems. An increase in phytoplankton levels can form toxic algal blooms that are harmful to humans, mammals, and aquatic creatures, while a decrease in phytoplankton levels can potentially lead to the extinction of many creatures within the ecosystem.

As tiny as they may be, phytoplankton sustain all life and many natural processes on Earth. The next time you take a breath of fresh air or indulge yourself with a delicious seafood feast, remember to think about our microscopic heroes and thank them for all that they do!